Ultraviolet irradiation improves the hydrophilicity and osteo-conduction of hydroxyapatite

Abstract

Background Treating a titanium or titanium alloy implant with ultraviolet (UV) light is known to improve its associated cell growth and osseointegration. However, little is known about the effect of UV irradiation on hydroxyapatite (HA), which is also used frequently in orthopaedic and dental surgery. Here we examined the effect of UV irradiation on the hydrophilicity of HA, and on its osteoconduction ability in rats. Methods HA implants of low and high porosity were treated with UV light, and photofunctionalisation was assessed by the contact angle of a water drop on the surface. HA implants were also inserted into rat femurs, and the rats were killed 2 or 4 weeks later. The bone volume and bone area ratio were calculated from microcomputed tomography and histological data. Results The contact angle of a water drop on HA implants of both porosities was significantly reduced after UV irradiation. In the rat femurs, there was no significant difference in the bone volume between the UV light-treated and control implants at 2 or 4 weeks. The bone area ratio for the UV light-treated versus control implants was significantly increased at 2 weeks, but there was no significant difference at 4 weeks. Conclusions The surface of UV-irradiated HA disks was hydrophilic, in contrast to that of non-irradiated HA disks. Photofunctionalisation accelerated the increase in the bone area ratio in the early healing stage. This technology can be applied to surgical cases requiring the early fusion of bone and HA.

Effect of UV Photofunctionalization of HA/TiO₂ Coated Implants Prepared by Dual-Target Sputtering on Bone-Implant Integration

“…UV irradiation reduces the amount of hydrocarbons on the Ti surface, and the hydrocarbon content strongly correlates with the rate of protein adsorption and cell attachment 16.17) . A similar phenomenon may occur in HA on the Hyb surface 29,30) . This may explain the relatively high bone-implant integration results for UV irradiated implants.…”

Multi-Level Evaluation of UV Action upon Vitamin D Enhanced, Silver Doped Hydroxyapatite Thin Films Deposited on Titanium Substrate

“…According to Ashish Yadav [77] the biological medium does not cause major corrosion of titanium and its alloy. On the other hand, previous studies [30][31][32]78] reported that the UV irradiation of the titanium or titanium alloys lead to a significant increase of the surface hydrophilicity and biological properties. Also, a similar behavior was noticed in the case of HAp disk [78].…”

“…On the other hand, previous studies [30][31][32]78] reported that the UV irradiation of the titanium or titanium alloys lead to a significant increase of the surface hydrophilicity and biological properties. Also, a similar behavior was noticed in the case of HAp disk [78]. Moreover, according to H. Nishikawa [30] the UV irradiation of the HAp surface could induce the formation of active radical species.…”

Generating bioactive and antiseptic interfaces with nano-silver hydroxyapatite-based coatings by pulsed electrochemical deposition for long-term efficient cervical soft tissue sealing

“…3), which might be ascribed to the favorable wettability and hydrophilicity of hydroxyl radicals in HA. 64 Although the slightly increased water contact angle in the Ag/2CaP group almost had no influence on its hydrophilicity, this result may be attributed to the flaws of the traditional contact angle measures. Conventional macroscopic contact angle measures fail to adequately capture properties of molecular surfaces or extended surfaces with heterogeneity and different surface topography at the nanometer length scales.…”